This invention relates to acoustic signal processing and is particularly directed to fine grain analysis of sonar signals for purposes of classification of the received signals.
It is now possible for a transducer array to "see" simultaneously in all directions. Signals from the several transducers of the array are processed through phase compensation networks and are so combined that signals will appear in separate circuits corresponding to different discrete directions, or beams.
The introduction into submarines of multi-beam sonars using preformed beams has posed additional requirements in the areas of detection and classification. It is, of course, desirable to instantly display all signals regardless of direction in sufficiently fine grain detail to enable the operator to classify the signal as to the type of ship, for example, from which the signal is received. While pre-formed beam systems have the advantage of making all of the incoming data instantly available for use, they must as a consequence require the handling of data in amounts which are increased by a direct factor of the number of pre-formed beams. Present classification methods based on fine grain spectrum analysis and long time integration may, if carried to their logical optimum, require that many millions of bits of data be handled and stored for a single beam.
The best techniques presently known in data analysis, storage and display makes it completely unfeasible from the standpoint of size, weight and cost to install aboard ship an optimum classification system for each beam of a multibeam sonar system. It is the purpose of this invention to propose a reasonable compromise among the various factors involved which will provide a nearly optimum detection and classification system.